Diesel fuel



Patented Jan. 23, l9fi0 DIESEL FUEL George S. Crandall, Woodbury, N. 1., asaignor to Socony-Vacuum Oil Company, Incorporated, New York, N. Y., a corporation of New York No Drawing. Application December .2, 1938,

Serial No. 243.507

9 Claims. (01. 44-9) This invention has to do in a general way with the operation of internal combustion engines and is more particularly concerned with improving the operation of engines operating on the Diesel 6 cycle by the use of 9. Diesel fuel which contains a characterizing ingredient that will improve the ignition quality of the fuel.

In engines which operate on the Diesel cycle, where the fuel is injected into compressed air in the cylinder and is ignited spontaneously, it is important that the delay period between injec tion and ignition be short so as to promote the ease of starting and smoothness of operation. Improperly delayed ignition gives rise to the phenomenon known as knocking.

This invention has as its object the improvement of the ignition quality of a Diesel fuel by the admixture with the fuel of a novel compound in suflicient proportion to decrease the ignition 20 delay period. The invention may also be defined as a method of improving the ignition quality of the fuel by adding to the fuel prior to its injection into the compressed air of the cylinder a minor proportion of this characterizing ingredient.

The use of an accelerator to decrease the ignition delay period of a Diesel fuel provides means for reducing the compression pressure at which spontaneous ignition. takes place and in this way permits engine designs of lesser mass or weight, thereby decreasing the cost of manufacture and operation per unit of power output. The use of these accelerators also widens the range of available Diesel fuels, since it not only 35 permits improving the ignition quality-of the fuels of the type normally .used but it provides 4a means for raising the quality of inferior grades of fuels into the range where they may be successfully employed.

This invention is predicated upon the discovery that certain organic nitrogen compounds falling into the class known as the substituted pentazdienes possess the property, when admixed in minor proportion with a hydrocarbon fuel oil of 45 the type ordinarily used in compression ignition engines, of effecting a substantial increase in the ignition quality of such fuel.

The pentazdienes, which are also known as bisdiazo amino compounds and as bi's-aryldiazo the trivalent pentazdiene group 55 This general class .of compounds may be con-' w Ber. 27, 705', (1894)..

amines, are all characterized by the presence of- The particular compounds contemplated by this invention as improving agents for Diesel fuel are characterized by the fact that the two end nitrogens of the pentazdiene characterizing group are attached to aryl groups, which may or 5 may not be otherwise substituted.

The third nitrogen in the pentazdiene group carries a hydrocarbon radical selected from the group consisting of: aryl radicals, aryl radicals substituted with other radicals such as alkyl groups, and alkyl and substituted alkyl radicals or groups. Qompounds falling into this representative class may be illustrated by the following general formula:

R" R-N=N-1 I- -'-N-a' in whichR and R represent radicals selected from the group consisting of aryl and substituted arylradicals and R." represents a radical selected from the group consisting, ofaryl, substituted aryl, alkyl or substituted alkyl radicals or groups.

The following list of pentazdienes .with literature references for methods of preparation is( representative of the compounds contemplated by this invention. It is to be understood, of course, that this list is merely illustrative and is not to be considered as in any way limiting the scope of the present invention.

A. 3-methyl-L5-diphenyl pentazdiene,

(Goldschmidt and Bad], Ber. 22, 9s4."(1aa9) B. 1,3,5,-triphenyl pentazdiene,

- Gran-N N=N (B amberger, Ber. 27, 2596,,(1890) C. 3-ethyl-l,5-di-p-tolyl pentazdiene,

(Goldschmidt and Holm. Ber. 21,1025, (isaan D. 1,3,5-tri-p-tolyl pentazdiene,

have been prepared by'the v. Pechman and 6 Frobenius method described above, two other methods have been used for preparing compounds B. andD. TheseQmethods involve (a) the interaction of an N-nitroso, N-acyl-aryl amide and a primary arylamine and (b) the interaction of a diaryl triazene (diazoamino compound) with an aryl diazonium salt.

The last-mentioned reaction may be illustrated by the equation:

The reaction which takes place in the general procedure first disclosed above, wherein two molecular proportions of a diazonium salt are reacted in acid solution with a primary amine, may be illustrated by the following equation:

The following examples illustrate the procedure which may be followed in the preparation of the pentazdiene compounds contemplated herein as accelerators for Diesel fuels.

Forty-four parts by weight of para toluidine is diazotized in the well-known manner in aqueous acid solution with just suflicient sodium nitrite solution to give a slight excess of nitrous acid persisting. for ten minutes after the last addition of nitrite solution as shown by test with starch iodide .paper. The diazotization is carried out at a temperature of from ,l to 0 0., and the product of this reaction is toluene diazonium chloride. To the chilled solution of toluene diazonium chloride isadded a solution of ten parts ,by weight of ethyl amine in ninety parts by weight of diluted (about eighteen per cent) aqueous hydrochloric acid, the temperature of the reaction solution being maintained between 0 and 15 C. by the addition of ice. The reaction mixture is carefully neutralized with dilute sodium hydroxide to obtain a reaction product which separates as a solid and is removed by filtration. The filtrate is purified by recrystallization from hot alcohol, such purified product having a melting point of between 114 and 118 C.

To demonstrate the efiectiveness of the pentazdiene compounds contemplated by this invention as accelerators for Diesel fuel, we have subjected various blends of representative'pentazdienes in Diesel fuel base stock to the conventional test used in determining cetane numbers, which is indicative of the ignition quality of the fuel. This test involves comparison of the blended fuel with a standard reference fuel in a converted C. F. R. engine, using the ignition delay method. The "cetane number obtained is .the per cent by volume of cetane in a blend of of which are tabulated below in Table I, was a petroleum distillate commonly known as -No. 2 fuel oil having a flash point of 156 F., a specific gravity of 0.86, Lovibond color of 0.25, and a cetane number of 42. The table shows the con-, centration by weight of the compoundin the fuel, the cetane number of the fuel blend and the increase in cetane number efiectedby the added agent over that of the fuel alone:

It will be seen from the foregoing table that the substituted pentazdienes, of which the compounds listed in the table are representative, are effective to substantially improve the ignition quality of 9. Diesel fuel when added thereto in minor proportions. The amount of compound used may be varied depending upon the original base stock and the extent of the improvement which is desired. In general it appears that amounts ranging from 0.5 to 1.0 per cent will effect the desired improvement, but the invention contemplates the addition of amounts ranging from 0.01 per cent to per cent.

It is to be understood that the term "Diesel fuel as used herein has reference to any hydrocarbon fuel adapted for use in an engine operating according to the Diesel cycle.

I claim:

1. An improved Diesel fuel having in admixture therewith a minor proportion of a substituted pentazdiene in sufficient amount to decrease the ignition delay period of the fuel.

2. An improved Diesel fuel having in admixture therewith .a minor proportion of a 3-alkyl-1, 5-diaryl pentazdiene in sufficient amount to decrease the ignition delay period of the fuel.

3. An improved Diesel fuel having in admixture therewith a minor proportion of a 1, 3, S-triaryl pentazdiene in sufiicient amount to decrease the ignition delay period of the fuel.

4. An improved Diesel fuel having in admixture therewith a minor proportion of a compound having the general formula in which R and R represent aryl radicals or substituted aryl radicals and in which R" represents lected from the group consisting of 3-methyl-1,

5-diphenyl pent'azdiene; 1, 3,.i-triphenyl pentazdiene; 3-ethyl-1, 5-di-p-tolyl pentazdiene; and 1, 3, 5-tri-p tolyl pentazdiene, said compound being present in the fuel in an amount sufficient to decrease the ignition delay period of the fuel.

6. The method of accelerating the ignition of a liquid hydrocarbon fuel in an engine where the fuel is injected into compressed air in the engine cylinder and ignites spontaneously therein, which comprises admixing with the fuel, prior to its injection 'into the cylinder, a minor proportion of a'pentazdiene.

7. The method of accelerating the ignitionof a liquid hydrocarbon fuel in an engine where the fuel is injected into compressed air in the engine cylinder and ignites spontaneously therein, which comprises admixing with the fuel, prior to its injection into the cylinder, a minor proportion of a 3-alkyl-1, 5-diaryl pentazdiene.

8. The method of accelerating the ignition of a liquid hydrocarbon fuel in an engine where the fuel is injected into compressed air in the engine cylinder and ignites spontaneously therein, which comprises admixing with the fuel, prior to its injection into the cylinder, a minor proportion of a 1, 3, 5-triary1 pentazdiene.

9. The method of accelerating the ignition of a liquid hydrocarbon fuelin an engine where the fuel is injected into compressed air in the engine cylinder and ignites spontaneously therein, which comprises admixing with the fuel, prior to its injection into the cylinder, 9. minor proportion of a compound having the general formula RN=NNN=NR' in which R. and R represent aryl radicals or sub stituted aryl radicals, and in which R" represents a radical selected from the group consisting of aryl, substituted aryl, alkyl and substituted alkyl radicals.

GEORGE S. CRANDALL. 

